Lowland Amazonian Forests Research Articles

Sharp declines in observation and capture rates of Amazon birds in absence of human disturbance

Across the globe, unprecedented declines have been reported across a range of taxa. Among the most well documented are declines in bird populations, with most declines attributable to human activities such as deforestation and other alterations to habitats. There is increasing evidence that bird populations also have declined at sites within large expanses of relatively undisturbed lowland tropical forest, such as in Amazonia. Causes of such declines likely are varied and may be related to direct or indirect effects of climate change. Here, we use mist-net data and direct observations to examine changes in bird numbers over a 22-yr period on two 100-ha study plots in an Amazonian lowland forest of eastern Ecuador. As previously reported, capture rates experienced large declines from 2009 on; observation rates also showed large declines through 2013 but subsequently have shown no consistent trend up or down. Overall capture rates and observation rates are now approximately half the rates during the first decade. Most foraging guilds also declined over time, with declines particularly pronounced among insectivorous groups. With few exceptions, patterns of change were similar between plots suggesting a more general response rather than responses to local factors on each plot. Capture rates and observation rates of ∼90% of the most common species in both understory and canopy were lower during the latter part of the study, with only a few species (∼10%) showing increases. Similarly, large declines were seen in both canopy and understory mixed-species flocks. Large declines in bird numbers have been noted in other tropical sites that have conducted long-term population studies, including Panama and Brazil, suggesting a response to large-scale factors, such as climate change. While not yet documented, the consequences of losing approximately 50% of population abundance are likely substantial and could result in local extinction of rare species, altered species interactions and social organization, as well as declining ecological function and biotic integrity of these tropical forest ecosystems.

Predicting ecosystem productivity based on plant community traits.

With the rapid accumulation of plant trait data, major opportunities have arisen for the integration of these data into predicting ecosystem primary productivity across a range of spatial extents. Traditionally, traits have been used to explain physiological productivity at cell, organ, or plant scales, but scaling up to the ecosystem scale has remained challenging. Here, we show the need to combine measures of community-level traits and environmental factors to predict ecosystem productivity at landscape or biogeographic scales. We show how theory can extend the production ecology equation to enormous potential for integrating traits into ecological models that estimate productivity-related ecosystem functions across ecological scales and to anticipate the response of terrestrial ecosystems to global change.

Humipedon dynamics in lowland Amazonian forests: are there Amphi humus forms even in tropical rain forests?

Understanding humipedon dynamics is crucial to capture forest ecological processes. However, studies disentangling humipedon dynamics in tropical forests are scarce. The humipedon structure classification is important because it shows how forest ecosystems interact and react with (a)biotic factors. Here, we used the humus morpho-functional approach to investigate how soil texture and reduced impact-logging affect forest humipedon structure and dynamics in the eastern Amazon. We used a morpho-functional classification of humus forms as the foundation to visualize, classify, and code 133 soil profiles in two contrasting soil textures and different post-logging practices, to identify litter leaching, fragmentation, and humification processes coupled with soil aggregation and root dynamics. The classification of humus forms resulted in the identification of three humus systems: Mull, Moder and Amphi. Sandy and clayey textures differ statistically (χ2 = 51.83; p < 0.001), with sandy texture predominating in Moder system, while clayey texture exhibits Amphi or Mull systems. Sandy textures presented a weak soil aggregation, but strong association with root (rhiOF) and humification (OH) horizons, leading to a clear transition between organic and mineral pools. In contrast, clayey textures show a strong carbon storage and soil aggregation. The humipedon horizons differ significantly (p = 0.009; stress = 0.1142 and R2 = 0.987) and their dynamics clearly evolve towards an opposite direction. The classification framework introduced here supports environmental management by promoting speed and viability in diagnosing forest ecosystem soils towards forest protection or use in the landscape, and specific climate mitigation goals both in local and regional planning.

Two New Cryptic Pristimantis (Anura, Craugastoridae) from the Southern Amazon Basin of Peru with Taxonomic Comments on Pristimantis imitatrix (Duellman, 1978)

Fieldwork in premontane and lowland Amazonian forest (385–1,075 m above sea level) in and around the Amarakaeri Communal Reserve in southeastern Peru led us to describe two new species of the genus Pristimantis. We used integrative evidence from several external morphological characters, morphometric and molecular data, geographic distributions, and multivariate analyses to support the identification of these new species. Pristimantis gagliardi sp. nov. is characterized by lacking a visible tympanic annulus and membrane on skin, having basal webbing between toes, yellow blotches in groin and hidden surfaces of shanks, W-shaped scapular mark, snout subacuminate bearing a very small papilla at tip of snout, and snout–vent length (SVL) = 17.7–21.3 mm in adult males and SVL = 26.7–29.2 mm in females. Pristimantis okmoi sp. nov. is characterized by having a visible tympanic annulus and membrane on skin, basal webbing between toes, yellow blotches in groin and hidden surfaces of shanks, W-shaped scapular mark, snout rounded with small rostral papilla, and SVL = 13.63–17.04 mm in adult males; females unknown. Both species were initially misidentified as P. carvalhoi or P. imitatrix. Additionally, we provide new morphological and phylogenetic data on adult specimens of Pristimantis imitatrix, a rare Amazonian species described based on a single subadult female.

Water table level and soil texture are important drivers of dung beetle diversity in Amazonian lowland forests

The high biodiversity of the Amazon region is related to variation in soil physical properties and water-table depths. Dung beetles are efficient bioindicators that feed and breed on the soil surface and below ground, affecting soil properties and being affected by them. Here, we investigate the influence of soil physical characteristics (proportions of sand, silt, clay) and water-table depth on dung beetle assemblages and functional groups in a forest in central Amazonia. We sampled beetles in 29 transects with different soil physical properties and water-table maximum levels, and analyzed beetle species richness, abundance and species composition for the total assemblage and for each functional group (rollers, tunnellers, dwellers). Dung beetle abundance increased with soil clay content (GLMM; p = 0.009) whereas dweller (GLMM; p = 0.017) and tunneller species richness increased with clay and silt contents (GLMM; p = 0.018). Sites with deeper water table had greater roller-beetle abundance (GLMM; p = 0.049). Dung beetle assemblage composition was strongly influenced by clay content. Our results suggest that soil texture and water-table levels determine dung beetle distributions, both for the whole assemblages and for each functional group separately. These findings highlight the role of soil structure in determining dung beetle assemblages.

Contribution of Vouacapoua americana fruit-fall to the release of biomass in a lowland Amazon forest

Fruit-fall provides the transfer of biomass and nutrients between forest strata and remains a poorly understood component of Amazon forest systems. Here we detail fruit-fall patterns including those of Vouacapoua americana a Critically Endangered timber species across 25 km2 of lowland Amazon forest in 2016. We use multi-model comparisons and an ensemble model to explain and interpolate fruit-fall data collected in 90 plots (totaling 4.42 ha). By comparing patterns in relation to observed and remotely sensed biomass estimates we establish the seasonal contribution of V. americana fruit-fall biomass. Overall fruit-fall biomass was 44.84 kg ha−1 month−1 from an average of 44.55 species per hectare, with V. americana dominating both the number and biomass of fallen fruits (43% and 64%, number and biomass respectively). Spatially explicit interpolations provided an estimate of 114 Mg dry biomass of V. americana fruit-fall across the 25 km2 area. This quantity represents the rapid transfer by a single species of between 0.01 and 0.02% of the overall above ground standing biomass in the area. These findings support calls for a more detailed understanding of the contribution of individual species to carbon and nutrient flows in tropical forest systems needed to evaluate the impacts of population declines predicted from short (< 65 year) logging cycles.

Distributional patterns of the Brazilian free-tailed bat Tadarida brasiliensis in the Peruvian territory

The molossid bat Tadarida brasiliensis has a wide and apparently continuous distribution in South America. Although it has been reported in several localities of both versants of the Peruvian Andes, the potential distribution for this species has not been formally analyzed. Therefore, we describe its distributional pattern in the territory and provide comments about the possible influence of the Andes in its distribution. We gathered occurrence records from museums, acoustic surveys, literature, GBIF and Vertnet sources, and we selected localities to minimize spatial correlation. After defining a minimum-convex polygon of Peruvian records as background area, we use Maxent software with bioclimatic variables to construct species distribution models. Several models were evaluated using different metrics, and the model with the lowest AICc was selected. Then, the model was projected for Peruvian territory. Tadarida brasiliensis is reported for the first time in Cajamarca, Piura and Ica departments. The potential distribution model showed two disjunct suitable areas, one for the Pacific versant and other for the Amazonian versant of the Andes, but connected with moderate suitable conditions in the Huancabamba Depression region in northern Peru. Mean diurnal range and annual mean temperature were identified as the main limiting factors for the potential distribution of this species in this territory. Tadarida brasiliensis exhibits a discontinuous distribution in the Peruvian territory. In northern part, the Huancabamba depression zone has climatic conditions that may allow the east-west dispersal for this species. In central and southern parts, the higher crest of the Andes (> 4,500 m) has low suitable conditions due to the extreme climate. In the eastern, the lowland Amazonian forests has low suitability for this species, probably due to high temperatures. We suggest that the Andes could be acting a biogeographical barrier that limits the dispersal for this species, but population-genetic studies are needed to confirm this hypothesis. We identified that temperature is the main climatic factor that limit the dispersal of this bat. In conclusion, T. brasiliensis is mainly associated with desert and Andean slopes ecosystems in Peru, and we highlight the importance of incorporating acoustic records in the analysis of its distribution patterns.

The Amapá treefrog Boana dentei (Bokermann, 1967): diagnosis and redescription (Hylinae: Cophomantini)

ABSTRACT Many aspects of the Amazonian amphibian fauna are yet understudied. This is the case of the Amapá treefrog, Boana dentei, which was described in the 1960s based on a single female specimen from Serra do Navio, a Brazilian region of lowland Amazonian forests in the easternmost portion of the Guiana Shield. The species has been reported only a few times since its description, and phenotypic data from its type locality still remain unknown. We redescribe this treefrog species, including the first characterisation of the male, life colours, tadpole, vocalisation, and notes on habitat, based on a newly collected series from the type locality. Boana dentei is sexually dimorphic with respect to external morphology and colour patterns. Males are distinguished from females by a smaller snout–vent length, lighter dorsal colouration, bright yellow colour in ventral hindlimbs and palm of hand, and enlarged prepollex. Boana dentei is distinguished from other members of the B. albopunctata group by the snout truncate from above and rounded to vertical in profile, calcar absent on heel, black vertical bars on thigh, and vocal repertoire composed of three types of pulsed notes.

Advertisement calls, intraspecific variation and species diagnosis of six Brazilian species of Elachistocleis (Anura: Microhylidae: Gastrophryninae)

We describe for the first time the advertisement calls of three Elachistocleis species (E. surumu, E. magna, E. carvalhoi) and provide additional data on the calls of three other species (E. matogrosso, E. helianneae, E. muiraquitan). Additionally, we evaluate intraspecific variation in morphology and color patterns, and comment on species diagnosis in the genus. The advertisement calls of the six species of Elachistocleis have a stereotyped temporal and spectral structure, which consists of a long sustained multipulsed note with an upsweep in frequency at its onset, followed by a constant frequency along the note. Newly collected Elachistocleis from northern and western Brazil showed intraspecific variation in morphology and coloration that had not been previously reported. Coloration was listed as a diagnostic feature in the original descriptions of the Elachistocleis species evaluated in this study, but color patterns were variable in some species and sometimes did not allow for species differentiation. Our results indicated that the three species with greater degrees of morphological similarity (E. helianneae, E. matogrosso, E. muiraquitan) differed in microtemporal and spectral traits of their calls. Moreover, pulse duration in E. helianneae was very distinct, lasting approximately twice the average pulse duration in calls of the other species studied. Therefore, pulse duration might be an informative trait when assigning specimens to E. helianneae, which is widely distributed across Amazonian lowland forests and in a region of Amazonian savanna. Our results bring novelties on species diagnosis and intraspecific variation in Elachistocleis based on acoustic evidence and morphological/color patterns, and accentuate the importance of taking into consideration multiple lines of evidence as a means for accurate species-level identification in this genus of Neotropical frogs.

Compositional response of Amazon forests to climate change.

Most of the planet's diversity is concentrated in the tropics, which includes many regions undergoing rapid climate change. Yet, while climate‐induced biodiversity changes are widely documented elsewhere, few studies have addressed this issue for lowland tropical ecosystems. Here we investigate whether the floristic and functional composition of intact lowland Amazonian forests have been changing by evaluating records from 106 long‐term inventory plots spanning 30 years. We analyse three traits that have been hypothesized to respond to different environmental drivers (increase in moisture stress and atmospheric CO 2 concentrations): maximum tree size, biogeographic water‐deficit affiliation and wood density. Tree communities have become increasingly dominated by large‐statured taxa, but to date there has been no detectable change in mean wood density or water deficit affiliation at the community level, despite most forest plots having experienced an intensification of the dry season. However, among newly recruited trees, dry‐affiliated genera have become more abundant, while the mortality of wet‐affiliated genera has increased in those plots where the dry season has intensified most. Thus, a slow shift to a more dry‐affiliated Amazonia is underway, with changes in compositional dynamics (recruits and mortality) consistent with climate‐change drivers, but yet to significantly impact whole‐community composition. The Amazon observational record suggests that the increase in atmospheric CO 2 is driving a shift within tree communities to large‐statured species and that climate changes to date will impact forest composition, but long generation times of tropical trees mean that biodiversity change is lagging behind climate change.

Drought-induced Amazonian wildfires instigate a decadal-scale disruption of forest carbon dynamics.

Drought-induced wildfires have increased in frequency and extent over the tropics. Yet, the long-term (greater than 10 years) responses of Amazonian lowland forests to fire disturbance are poorly known. To understand post-fire forest biomass dynamics, and to assess the time required for fire-affected forests to recover to pre-disturbance levels, we combined 16 single with 182 multiple forest census into a unique large-scale and long-term dataset across the Brazilian Amazonia. We quantified biomass, mortality and wood productivity of burned plots along a chronosequence of up to 31 years post-fire and compared to surrounding unburned plots measured simultaneously. Stem mortality and growth were assessed among functional groups. At the plot level, we found that fire-affected forests have biomass levels 24.8 ± 6.9% below the biomass value of unburned control plots after 31 years. This lower biomass state results from the elevated levels of biomass loss through mortality, which is not sufficiently compensated for by wood productivity (incremental growth + recruitment). At the stem level, we found major changes in mortality and growth rates up to 11 years post-fire. The post-fire stem mortality rates exceeded unburned control plots by 680% (i.e. greater than 40 cm diameter at breast height (DBH); 5-8 years since last fire) and 315% (i.e. greater than 0.7 g cm-3 wood density; 0.75-4 years since last fire). Our findings indicate that wildfires in humid tropical forests can significantly reduce forest biomass for decades by enhancing mortality rates of all trees, including large and high wood density trees, which store the largest amount of biomass in old-growth forests. This assessment of stem dynamics, therefore, demonstrates that wildfires slow down or stall the post-fire recovery of Amazonian forests.This article is part of a discussion meeting issue 'The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications'.

Diversity of terrestrial mammal seed dispersers along a lowland Amazon forest regrowth gradient.

There is increasing interest in the restoration/regeneration of degraded tropical habitats yet the potential role of natural regenerators remains unclear. We test the hypothesis that the richness and functional diversity of terrestrial mammals differs between forest regrowth stages. We quantified the richness and functional diversity of eight terrestrial mammal seed-disperser species across a forest regrowth gradient in the eastern Brazilian Amazon. We installed camera-traps in 15 sites within small-holder properties with forest regrowth stage classified into three groups, with five sites each of: late second-regrowth forest, early second-regrowth forest and abandoned pasture. Species richness and functional dispersion from the regrowth sites were compared with 15 paired forest control sites. Multi model selection showed that regrowth class was more important for explaining patterns in richness and functional diversity than other variables from three non-mutually exclusive hypotheses: hunting (distance to house, distance to river, distance to town, small holder residence), land cover (% forest cover within 50 meters, 1 kilometer and 5 kilometers) and land use (regrowth class, time since last use). Differences in functional diversity were most strongly explained by a loss of body mass. We found that diversity in regrowth sites could be similar to control sites even in some early-second regrowth areas. This finding suggests that when surrounded by large intact forest areas the richness and functional diversity close to human small-holdings can return to pre-degradation values. Yet we also found a significant reduction in richness and functional diversity in more intensely degraded pasture sites. This reduction in richness and functional diversity may limit the potential for regeneration and increase costs for ecological regeneration and restoration actions around more intense regrowth areas.

Did Sea-Level Changes Affect the Brazilian Amazon Forest during the Holocene?

ABSTRACTIn order to contribute to the discussion of Holocene climate changes, four sediment cores were collected from the northern Brazilian Amazonia lowland. These cores were studied through pollen analysis and sedimentary features, and the results were discussed within a chronological framework provided by radiocarbon dating. The cores were sampled from fluvial terraces representative of channel, floodplain/lake and crevasse splay deposits formed since the mid-Holocene. The pollen samples derive from floodplain/lake deposits and the pollen grains are mainly composed by families Moraceae, Euphorbiaceae, Caesalpiniaceae, Fabaceae, Rubiaceae, Melastomataceae, Combretaceae, Sapindaceae, Poaceae, Cyperaceae, Aizoaceae, Apiaceae and genusSebastiana. The pollen data suggest no significant vegetation changes in the study area for the past 4808–4886 cal yr BP. This led to proposing stable climatic conditions since at least the middle Holocene. Such a finding is contrary to the occurrence of a dry period during the middle Holocene. The stabilization of the relative sea level about 6000 cal yr BP along the northern Brazilian littoral may have influenced the water table, and favored the establishment and maintenance of Amazonian lowland forest during the mid- and late Holocene. In addition, this process may have attenuated the impact of that dry period in areas under most fluvial influence.

First record of Boana alfaroi (Caminer &amp;amp; Ron, 2014) (Anura:&amp;nbsp;Hylidae) in Brazil

We report the occurrence of the Amazonian hylid Boana alfaroi outside of Ecuador for the first &nbsp;time. The locality&nbsp;(Assis Brasil, state of Acre) lies in northern Brazil, approximately 1,280 km southeast from the easternmost records in Ecuador. Additionally, we describe the vocalization of a male of B. alfaroi&nbsp;from the Brazilian population, including a second type of note besides the advertisement note.&nbsp;Boana alfaroi may occur across Amazonian lowland forests of&nbsp;Ecuador, northern Peru, and the Brazilian states of Acre and Amazonas.&nbsp

A New Species of Nectar-Feeding Bat of the GenusHsunycteris(Phyllostomidae: Lonchophyllinae) from Northeastern Peru

ABSTRACT A new species of the nectarivorous bat genus Hsunycteris is described from lowland Amazonian forest in northeastern Peru. The new species, H. dashe, can be distinguished from other congeners by its larger size; V-shaped array of dermal chin papillae separated by a wide basal cleft; metacarpal V longer than metacarpal IV; broad rostrum; lateral margin of infraorbital foramen not projecting beyond rostral outline in dorsal view; well-developed sphenoidal crest; large outer upper incisors; weakly developed lingual cusp on P5; and well-developed, labially oriented M1 parastyle. A phylogenetic analysis of cytochrome-b sequence data indicates that H. dashe is sister to a clade that includes all other species of the genus including H. cadenai, H pattoni, and a paraphyletic H. thomasi. We provide a key based on craniodental and external characters of all four known species of Hsunycteris.

A free-access online key to identify Amazonian ferns.

There is urgent need for more data on species distributions in order to improve conservation planning. A crucial but challenging aspect of producing high-quality data is the correct identification of organisms. Traditional printed floras and dichotomous keys are difficult to use for someone not familiar with the technical jargon. In poorly known areas, such as Amazonia, they also become quickly outdated as new species are described or ranges extended. Recently, online tools have allowed developing dynamic, interactive, and accessible keys that make species identification possible for a broader public. In order to facilitate identifying plants collected in field inventories, we developed an internet-based free-access tool to identify Amazonian fern species. We focused on ferns, because they are easy to collect and their edaphic affinities are relatively well known, so they can be used as an indicator group for habitat mapping. Our key includes 302 terrestrial and aquatic entities mainly from lowland Amazonian forests. It is a free-access key, so the user can freely choose which morphological features to use and in which order to assess them. All taxa are richly illustrated, so specimens can be identified by a combination of character choices, visual comparison, and written descriptions. The identification tool was developed in Lucid 3.5 software and it is available at http://keyserver.lucidcentral.org:8080/sandbox/keys.jsp.

Water availability not fruitfall modulates the dry season distribution of frugivorous terrestrial vertebrates in a lowland Amazon forest.

Terrestrial vertebrate frugivores constitute one of the major guilds in tropical forests. Previous studies show that the meso-scale distribution of this group is only weakly explained by variables such as altitude and tree basal area in lowland Amazon forests. For the first time we test whether seasonally limiting resources (water and fallen fruit) affect the dry season distribution in 25 species of terrestrial vertebrates. To examine the effects of the spatial availability of fruit and water on terrestrial vertebrates we used a standardized, regularly spaced arrangement of camera-traps within 25km2 of lowland Amazon forest. Generalized linear models (GLMs) were then used to examine the influence of four variables (altitude, distance to large rivers, distance to nearest water, and presence vs absence of fruits) on the number of photos on five functional groups (all frugivores, small, medium, large and very large frugivores) and on seven of the most abundant frugivore species (Cuniculus paca, Dasyprocta leporina, Mazama americana, Mazama nemorivaga, Myoprocta acouchy, Pecari tajacu and Psophia crepitans). A total of 279 independent photos of 25 species were obtained from 900 camera-trap days. For most species and three functional groups, the variation in the number of photos per camera was significantly but weakly explained by the GLMs (deviance explained ranging from 6.2 to 48.8%). Generally, we found that the presence of water availability was more important than the presence of fallen fruit for the groups and species studied. Medium frugivores, large-bodied frugivores, and two of the more abundant species (C. paca and P. crepitans) were recorded more frequently closer to water bodies; while none of the functional groups nor the most abundant species showed any significant relationship with the presence of fallen fruit. Two functional groups and two of the seven most common frugivore species assessed in the GLMs showed significant results with species-specific responses to altitude. Our findings provide a more detailed understanding of how frugivorous vertebrates cope with periods of water and fruit scarcity in lowland Amazon forests.

Evaluation of directional normalization methods for Landsat TM/ETM+ over primary Amazonian lowland forests

Biodiversity mapping in extensive tropical forest areas poses a major challenge for the interpretation of Landsat images, because floristically clearly distinct forest types may show little difference in reflectance. In such cases, the effects of the bidirectional reflection distribution function (BRDF) can be sufficiently strong to cause erroneous image interpretation and classification. Since the opening of the Landsat archive in 2008, several BRDF normalization methods for Landsat have been developed. The simplest of these consist of an empirical view angle normalization, whereas more complex approaches apply the semi-empirical Ross–Li BRDF model and the MODIS MCD43-series of products to normalize directional Landsat reflectance to standard view and solar angles. Here we quantify the effect of surface anisotropy on Landsat TM/ETM+ images over old-growth Amazonian forests, and evaluate five angular normalization approaches. Even for the narrow swath of the Landsat sensors, we observed directional effects in all spectral bands. Those normalization methods that are based on removing the surface reflectance gradient as observed in each image were adequate to normalize TM/ETM+ imagery to nadir viewing, but were less suitable for multitemporal analysis when the solar vector varied strongly among images. Approaches based on the MODIS BRDF model parameters successfully reduced directional effects in the visible bands, but removed only half of the systematic errors in the infrared bands. The best results were obtained when the semi-empirical BRDF model was calibrated using pairs of Landsat observation. This method produces a single set of BRDF parameters, which can then be used to operationally normalize Landsat TM/ETM+ imagery over Amazonian forests to nadir viewing and a standard solar configuration.

Branchfall dominates annual carbon flux across lowland Amazonian forests

Tropical forests play an important role in the global carbon cycle, but knowledge of interannual variation in the total tropical carbon flux and constituent carbon pools is highly uncertain. One such pool, branchfall, is an ecologically important dynamic with links to nutrient cycling, forest productivity, and drought. Identifying and quantifying branchfall over large areas would reveal the role of branchfall in carbon and nutrient cycling. Using data from repeat airborne light detection and ranging campaigns across a wide array of lowland Amazonian forest landscapes totaling nearly 100 000 ha, we find that upper canopy gaps—driven by branchfall—are pervasive features of every landscape studied, and are seven times more frequent than full tree mortality. Moreover, branchfall comprises a major carbon source on a landscape basis, exceeding that of tree mortality by 21%. On a per hectare basis, branchfall and tree mortality result in 0.65 and 0.72 Mg C ha−1 yr−1 gross source of carbon to the atmosphere, respectively. Reducing uncertainties in annual gross rates of tropical forest carbon flux, for example by incorporating large-scale branchfall dynamics, is crucial for effective policies that foster conservation and restoration of tropical forests. Additionally, large-scale branchfall mapping offers ecologists a new dimension of disturbance monitoring and potential new insights into ecosystem structure and function.

Diversity and Distribution of Ectomycorrhizal Fungi from Amazonian Lowland White‐sand Forests in Brazil and French Guiana

AbstractWhite‐sand forests are thought to host many ectomycorrhizal fungi, as demonstrated by the numerous fruiting body collections made by Rolf Singer in the lower Rio Negro in the late 1970s. Despite recognition of the importance of ectomycorrhizal fungi in white‐sand forests, there has not yet been a systematic examination of diversity and taxonomic composition across white‐sand forests, or more widely across lowland Amazonian forests. In an effort to broaden our view of ectomycorrhizal fungal diversity and distribution on white‐sand forests, we collected ectomycorrhizal fruiting bodies in 10 plots of white‐sand forests in Brazil and French Guiana between 2012 and 2014. We collected 221 specimens and 62 morphospecies, from the 10 plots, confirming that all studied white‐sand forests host ectomycorrhizal fungi. Additionally, we searched for taxa associated with white sands among specimens deposited in Brazilian herbaria. We report 1006 unique ectomycorrhizal specimen records in 18 Brazilian herbaria, of which 137 specimens and 64 species are reported from white‐sand forests, mainly in the state of Amazonas, Brazil. Russulaceae and Amanitaceae were frequent in all habitats, and Cortinarius were more frequent on white sands. Our results highlight the high diversity and heterogeneity of ectomycorrhizal communities on white‐sand forests, and the wide distribution of ectomycorrhizal fungi throughout Brazil, irrespective of soil type.